1. Field of the Invention
The present invention relates generally to devices and methods for the treatment of female urinary incontinence, and more particularly, to an improved surgical instrument and method that can be used to place a sub-urethral sling.
2. Background Discussion
Women account for more than 11 million of incontinence cases. Moreover, a majority of women with incontinence suffer from stress urinary incontinence (SUI). Women with SUI involuntarily lose urine during normal daily activities and movements, such as laughing, coughing, sneezing and regular exercise.
SUI may be caused by a functional defect of the tissue or ligaments connecting the vaginal wall with the pelvic muscles and pubic bone. Common causes include repetitive straining of the pelvic muscles, childbirth, loss of pelvic muscle tone, and estrogen loss. Such a defect results in an improperly functioning urethra. Unlike other types of incontinence, SUI is not a problem of the bladder.
Normally, the urethra, when properly supported by strong pelvic floor muscles and healthy connective tissue, maintains a tight seal to prevent involuntary loss of urine. When a woman suffers from the most common form of SUI, however, weakened muscle and pelvic tissues are unable to adequately support the urethra in its correct position. As a result, during normal movements when pressure is exerted on the bladder from the diaphragm, the urethra cannot retain its seal, permitting urine to escape. Because SUI is both embarrassing and unpredictable, many women with SUI avoid an active lifestyle and shy away from social situations.
One device and method for treating female urinary stress incontinence is described in detail in U.S. Pat. No. 5,899,909, which is incorporated herein by reference in its entirety. This patent discloses a surgical instrument comprising a shank having a handle at one end and connecting means at the other end to receive, one at a time, two curved needle-like elements which are connected at one end to one end of a mesh intended to be implanted into the body. In practice, the mesh is passed into the body via the vagina first at one end and then at the other end, at one side and the other, respectively, of the urethra to form a loop around the urethra, located between the urethra and vaginal wall. The mesh is extended over the pubis and through the abdominal wall and is tightened. The mesh ends are cut at the abdominal wall, and the mesh is left implanted in the body. This trans-vaginal procedure is exemplified by the TVT product sold by the Gynecare franchise of Ethicon Inc., a Johnson & Johnson Company, of Somerville, N.J., USA. In this procedure two 5 mm needles pass a PROLENE mesh trans-vaginally and through the abdomen to create a tension-free support around the mid urethra.
Sub-urethral slings have also been place by a different approach, wherein a needle is passed first though the abdominal wall, along the same path as described above, and eventually exiting through the vaginal incision. The tape is then coupled to the needle in some manner, and pulled back through the body from the vaginal incision and out through the abdominal incision. The chosen approach, vaginal or abdominal, will often depend on the preferences of the surgeon.
Yet another approach for implanting a sub-urethral sling has also been recently developed in which the implanted sling extends from beneath the urethra, and out through the obturator hole on either side. This “transobturator” procedure may involve inserting an appropriately configured needle from a vaginal incision and subsequently out through the obturator hole, or vice versa. The former technique (an “inside-out” approach) will be described in greater detail below, and has been performed using a surgical instrument substantially similar to that shown in FIG. 1. The surgical instrument 100 includes two surgical passers 101, 103 that are secured at a proximal end to handles 102, 104. The surgical passers are curved and form a somewhat helical shape, and are mirror images of one another so that one is particularly suited for passage through the body on one side of the urethra, whereas the other is particularly suited for passage on the opposite side of the urethra. Applied over the ends of the passers are tube elements 106, 108, proximal ends 109 of which are coupled to a tape 110 to be implanted. The tape is preferably of knitted mesh construction, such as Prolene® polypropylene mesh (manufactured by Ethicon, Inc. of Somerville, N.J.) having dimensions of approximately ½×18 inches. The tape is also preferably covered by a plastic sheath that overlaps in the middle section so as to be easily removable.
Previously, the tube elements were secured to the passers to enable passing of the tape into the body by press fitting the tube element onto the distal end of the passer. This attachment method does not allow pre-assembly (assembly prior to use), as sterilization gases (such as ethylene oxide) cannot effectively penetrate into the distal region of the passer and tube beyond where they are press-fit together. Pre-assembly is desirable to avoid product damage due to handling by hospital personnel, to best prevent multiple loose components on the surgical table, and also to prevent or reduce the risk of glove puncture by the sharp tips of the instrument. Further, even if effective sterilization was possible, because the tube element is preferably made of plastic, and would be subject to creep resulting from the constant pressure if pre-assembled, and may also be subject to stress cracking. Finally, manufacturing variations and moisture can have significant affects on press-fit components Thus, it would be desirable to provide an improved surgical assembly in which the surgical passer and tube element are secured together in a manner that enables pre-assembly, allows sterilization of the pre-assembled product, and is not subject to the other issues described above in conjunction with press-fit components.